Cups made of paper material and comprising a tubular wall and an outer sleeve are disclosed in the German laid-open patent application DE 10 2004 056 932 A1. In this reference, the tubular wall of the inner cup comprises a stacking shoulder which abruptly reduces the diameter of the inner cup. The stacking shoulder serves to ensure that the base bead of the outer sleeve of another cup of the same type rests against this stacking shoulder in the stacked state of the cups. The cup described in this reference has satisfactory stacking properties. However, any stacking shoulder or any other formation jutting inwardly or outwardly from the tubular wall of such a cup always results in a reduction in the strength of the paper material in the region of said formation. Such formations, when exposed to forces acting substantially in the axial direction; that is, in a direction parallel to the longitudinal center axis of the cup, may be regarded as being a flexible weak spot of the cup. In the case of very high stacks of cups or large double-walled cups, the tubular wall of the inner cup might well be deformed by such forces in the region of the deforming entity. Such deformation may also occur as a result of the cup being filled with large quantities of liquid, for example.
It is an object of the present invention to improve a cup made of paper material and to improve the method for fabrication of a paper cup.
To this end, according to the invention, a cup made of paper material is provided which has a fillable interior comprising an at least partially conical tubular wall and a bottom wall that is joined to the tubular wall at the bottom end of the interior of the cup in a substantially liquid-tight manner, wherein the tubular wall delimiting the interior has at least one deforming entity, whilst the cup comprises an outer sleeve at least partially surrounding the tubular wall, which outer sleeve is securely bonded to the tubular wall in a first region above the deforming entity and in a second region below the deforming entity.
Not only can such attachment of the outer sleeve to the tubular wall above and below the deforming entity compensate for the reduced material strength of the inner cup occurring as a result of the presence of the deforming entity but it can also significantly stabilize the cup in the region between the two bonded joints; that is, in the region of the deforming entity. Each of the bonded joints may consist, for example, of an adhesive joint involving the application of cold glue or hot-melt adhesive, a sealed joint, for example, involving the use of heat-sealing methods involving sealing wax or an already existing PE coating, with or without the interposition of spacer elements, a welded joint, or the like i.e. bonding by atomic or molecular forces. The outer sleeve or the casing stiffens the tubular wall, since it is joined to the latter above and below the deforming entity. The outer sleeve thus absorbs forces that would otherwise act exclusively or predominantly on the tubular wall in the absence of said two joints. The peripheral deforming entities provided, for example, for stacking the cups are thus more stable, and higher stacks of cups are thus made possible, that is to say, a greater number of cups can be stacked. The ability to destack the cups is maintained even following transportation over large distances. The cup stiffened in the manner proposed by the invention imparts a comfortable feel to the user, since the filled cup is more stable. More specifically, the outer sleeve can move only slightly or not at all toward the tubular wall of the inner cup when the user holds a filled cup of this type in the hand, which is not the case with a conventional cup not having the two joints provided by the invention. The stabilization of the tubular wall of the inner cup by the outer sleeve can also serve, for example, to make it possible to use material of reduced strength for the inner cup, since the stability of the inner cup is, of course, partly governed by the outer sleeve or the casing. According to the invention, it is possible to stiffen all types of peripheral deforming entities in a tubular wall of a paper cup by the provision of a joint between the outer sleeve and the tubular wall of the inner cup above and below the deforming entity. Apart from imparting a stiffening effect, the two joints can at the same time join the outer sleeve to the inner cup.
In a development of the invention, at least one of the joints between the tubular wall and the outer sleeve is provided by means of an adhesive fillet applied to the tubular wall and/or to the outer sleeve.
Cold glue or hot-melt adhesive can be used, for example. The adhesive fillet can be comparatively thick and it can be applied in the form of a so-called adhesive bead in order to space the outer sleeve and the tubular wall from each even in the glued state thereof. Such a space can serve to improve the insulating properties of the paper cup.
In a development of the invention, at least one of the joints comprises a plurality of regions disposed successively as regarded in the peripheral direction of the tubular wall and outer sleeve.
In this way, the outer sleeve can be joined to the tubular wall around the periphery of the tubular wall and the outer sleeve in a first region above, and in a second region below, the deforming entity. Thus the inner cup can be stabilized in the region of the deforming entity substantially around the entire periphery of the outer sleeve and the tubular wall of the inner cup. The joint between the tubular wall and the outer sleeve stiffens the deforming entity considerably when the joints are provided just above and just below the deforming entity, for example within a region of centimeter width above and below the deforming entity. However, the use of a joint beyond this region is still effective for stabilization of the deforming entity.
In a development of the invention, at least one of the joints is provided around the entire periphery of the tubular wall and the outer sleeve.
In this way, the inner cup can be significantly stiffened around the entire periphery thereof.
In a development of the invention, the outer sleeve is located at a distance from the tubular wall, at least in certain regions.
In this way, satisfactory insulating properties are achieved. The glued joint can then be produced by means of an adhesive bead that joins together and glues the surfaces of the outer sleeve and the tubular wall located in spaced relationship to each other. In particular, the tubular wall and/or the outer sleeve are alternatively provided with spacer elements that are also joined or glued. Advantageously, the spacer elements are oriented in a direction extending from the tubular wall toward the environment. The spacer elements can be in the form of components that are not part of the tubular wall or the outer sleeve.
In a development of the invention, the deforming entity is in the form of a means for supporting a cup of the same type in the stacked state of a plurality of cups. Especially peripheral deforming entities implemented for stacking the cups are exposed to large stacking loads occurring in high stacks of cups. It is precisely in the case of such peripheral deforming entities that the invention can be used with great success.
In a development of the invention, the bottom wall and the tubular wall form a peripheral edge frame in the region of the liquid-tight joint, the deforming entity being in the form of a means for supporting the peripheral edge frame of another cup of the same type in the stacked state of a plurality of cups.
Very good stacking properties can be achieved by the use of the peripheral edge frame for stacking the cups, but the peripheral deforming entities of each of the lower cups are also exposed to heavy loads in the axial direction. The gluing of the outer sleeve to the tubular wall of the inner cup in a first region above, and in a second region below, the deforming entity, as proposed by the invention, can clearly improve the stacking properties in this case or it can make it possible to fabricate the tubular sleeve of the inner cup using a thinner material.
In a development of the invention, the cup comprises an outer sleeve that surrounds the tubular wall at least in part, the deforming entity being in the form of a means for supporting the outer sleeve of a cup of the same type in the stacked state of a plurality of cups.
Even when numerous cups are stacked by means of the bottom edge of each of the outer cups, the invention can significantly improve the stacking properties of such cups.
In a development of the invention, the deforming entity represents a constriction, at least in certain regions, in the cross-section of the interior of the cup, when regarded in the direction of extending from the open end of the cup to the bottom wall.
In this way, the cups can be securely stacked, but such a constricted cross-section also results in a noticeable reduction in the strength of the material. In this case, the invention can combine the satisfactory stacking properties of such a constricted cross-section with significant stabilization of the tubular wall of the inner cup in the region of the deforming entity.
In a development of the invention, the outer sleeve rests with its bottom edge against the external surface of the peripheral edge frame and the lower joint between the outer sleeve and the tubular wall is disposed below the deforming entity and above the bottom wall.
In this way, forces acting axially or substantially parallel to the outer sleeve and in the tubular wall of the inner cup are absorbed by the inner cup not only by way of the bonded joints but also by way of the bottom edge of the outer sleeve. In this way, the outer sleeve rests, at least in the region of its bottom edge and also in the region of the two joints, against the tubular wall of the inner cup. Thus the cup of the invention forms a particularly stable unit.
The object of the invention is also achieved by a method for the production of a cup made of paper material, which method includes the following steps: joining a conical tubular wall to the bottom wall of a cup in a substantially liquid-tight manner, incorporating a deforming entity in the tubular wall, and securely bonding an outer sleeve to the tubular wall in a first region above the deforming entity and in a second region below the deforming entity.
In a development of the invention, provision is made for shaping an outer sleeve into a conical component, arranging material for achieving the bonded joint on the conical tubular wall and/or on the outer sleeve of the cup at least in a first region above the deforming entity and in a second region below the deforming entity and sliding the conical component onto the cup, and gluing the conical component to the cup.
In this way, the outer sleeve can be glued to the tubular wall of the inner cup at the same time as the conical component is pushed onto the cup. This leads to very rapid and economic fabrication of the paper cup of the invention. The material applied for achieving the bonded joint may be, for example, an adhesive, sealing wax or a sealable or weldable coating of plastics material or use may be made of the already existing coating on the paper material.
In a development of the invention, the material for achieving the bonded joint is disposed on the conical tubular wall and/or the outer sleeve of the cup at least in a first region above the deforming entity and in a second region below the deforming entity, and a paper blank designed to form the outer sleeve is positioned around the conical tubular wall.
The double-walled cup of the invention may also be produced by shaping a blank to form the outer sleeve, and the cup is finished at the same time as the outer sleeve is joined to the tubular wall of the inner cup while the inner cup is at the same time stabilized in the region of the deforming entity. The material for producing the bonded joint can be applied in the peripheral direction or alternatively at right angles thereto, for example in the form of an adhesive fillet. The application of glue at right angles to the peripheral direction can additionally stabilize the deforming entity by means of the material itself, particularly the adhesive, as applied for achieving the bonded joint.
Additional features and advantages of the invention are revealed in the claims and in the following description of preferred embodiments of the invention, with reference to the drawings. Individual features of the various embodiments shown can be combined as required without going beyond the scope of the present invention.